In general, the processing of a silver halide color photographic material comprises a color development step and a desilvering step. In the latter desilvering step, the developed silver formed in the color development step is oxidized to a silver salt with a bleaching agent having an oxidizing ability (bleaching), and the silver salt is then removed from the photographic layer by a fixing agent which forms soluble silver along with the non-used silver halide (fixation). Bleaching and fixation are effected either independently as separate bleaching and fixing steps, or simultaneously as a bleach-fixing step. The details of the processing steps are described in James, The Theory of Photographic Process, 4th Ed. (1977).
The above-described processing is generally carried out using an automatic developing machine. Recently, the use of a small-sized automatic developing machine called a mini-laboratory in photo processing shops has become popular for providing rapid processing service to customers.
Under these circumstances, rapid processing of photographic materials is presently in strong demand, such that further enhancements in rapid processing of the bleaching step, fixing step and bleach-fixing step are increasingly desired.
Since photographic processing has come to be carried out in various places, treatment of the waste liquid generated from the processing has become a serious problem.
Ferric ethylenediaminetetraacetate complex which has heretofore been used in a bleaching step has a fatal drawback characterized by a weak oxidizing capacity. Even when concurrently using a bleaching accelerator, the ferric complex still does not provide rapid bleaching.
Known bleaching agents useful for rapid bleaching include red prussiate of potash, iron chloride and bromates. However, these bleaching agents can not be widely used due to various problems. Particularly, red prussiate of potash causes environmental pollution; iron chloride causes corrosion of metals; and bromates are unstable in the form of a solution thereof. Accordingly, bleaching agents are desired which provide rapid bleaching, which can be handled with ease and which are free from the problem of generating harmful wastes.
Recently, as a bleaching agent satisfying the above-described conditions, ferric 1,3-diaminopropanetetraacetate complex has been proposed. However, this bleaching agent causes bleaching fog, and therefore is not entirely satisfactory.
On the other hand, thiosulfates are generally used as a fixing agent in a fixing step. However, the salts are oxidized and decompose to form sulfide precipitates. In most cases, therefore, sulfites are added to the step as a preservative for preventing oxidation and deterioration of the fixing agent. Further improvement of the stability of the fixing processing liquid is desired, while also reducing the replenishment amount. When an elevated amount of sulfites is added to the fixing step to reduce the amount of replenisher thereto, the additional sulfite does not fully dissolve in the bath or tends to be oxidized to form salt cake precipitates. In order to overcome these problems and to attain rapid processing, compounds having a better fixing capacity than thiosulfates are desired.
In processing color photographic papers, the bleaching agent and the fixing agent are contained in a common bath as a bleach-fixing bath, for attaining rapid processing. The bleaching agent generally used in this case is a ferric ethylenediaminetetraacetate complex. Recently, in order to further advance rapid processing, an oxidizing agent having a higher oxidizing power (or having a higher redox potential), such as ferric 1,3-diaminopropanetetraacetate complex, has been used in a bleach-fixing bath. However, the above noted oxidizing agent causes extreme bleaching fog and further contributes to oxidation and deterioration of thiosulfates in the bath, and is therefore not practically useful. In particular, the problems of the complex, as an oxidizing agent, are inconsistent with the development of processing systems using a reduced amount of replenisher.
In view of the above, the development of a bleaching agent and fixing agent which are free from the above-described problems and a processing composition containing the same, as well as a processing method using these processing compositions is highly desired.